Mobile data transmission and data services are constantly making progress. With the increasing penetration of such services, the need for increased bandwidth also increases. However, for standardized telecommunication systems, there is always a specifically assigned bandwidth (also known as licensed IMT-band) within the entire radio bandwidth for use by that system for mobile, i.e. wireless, communication. The present invention relates to such an environment of a telecommunication system such as for example LTE (Long Term Evolution) or LTE advanced, LTE-A, system or subsequent versions thereof. Those are referred to as mere examples only and others could likewise benefit from the present invention described herein below.
In particular, one approach to cope with the increased need for data transmission and correspondingly increased need of transmission bandwidth is known as a concept of carrier aggregation (CA). In connection with carrier aggregation, data transmission between a network transceiver device (such as a base station BS, NodeB, or evolved NodeB, eNB) and a user terminal, such as a mobile station MS or user equipment UE, makes use of bandwidth within the licensed band (e.g. the IMT band allocated/reserved for that purpose and/or telecommunication system by the International Telecommunication Union (ITU)) as well as of bandwidth different from (e.g. out of) that band denoted as non-IMT band (i.e. license-exempt band or a band licensed to other services/systems). Herein below, for simplicity, it is referred to an IMT band (as an example of licensed band for the telecommunication system) and non-IMT band (representing a different band, not licensed for mobile communication systems like GSM, UMTS, or LTE/LTE-A; i.e. license-exempt bands or bands licensed to other services/systems). Examples of non-IMT bands are a C-band, a TV white space band, an ISM band (Industrial Scientific Medical), etc.
Hence, from the above it turns out that the present invention is related to a concept to be setup for LTE-A or a future version beyond LTE-A, e.g. within a subsequent release of 3GPP (e.g. 3GPP Rel-12 or later releases) (3GPP=3rd Generation Partnership Project). Specifically, the present invention is related to an extension from a current LTE-A scheme in terms of supporting utilization of additional band or bands, i.e. non-IMT-bands (e.g. C-band, TV white space band, ISM band) by an LTE-A base station/evolved NodeB, eNB, and user terminal UE having a capability referred to as cognitive radio capability (i.e. having an ability to realize that non-IMT bands are present and potentially available to expand communication bandwidth).
In 3GPP standardization, carrier aggregation technologies are used to aggregate several carriers (on maybe different bands) and then provide high data rate service for UE. Currently, however, only carrier aggregation for (licensed) IMT bands is standardized in 3GPP. However, utilization of non-IMT bands for an LTE-A system or beyond will very likely be introduced in a future release e.g. R12 or later.
In view of carrier aggregation based on IMT bands, being already known, a repeated definition of principles applied by that technique is omitted here as a skilled reader is assumed to be familiar therewith as well as with related terminology, which—to the extent possible and without any intention of limiting the scope of the present invention—is used by way of example also in the present description for describing the present invention.
FIG. 1 shows a brief schematic of IMT and non-IMT band utilization over time t in carrier aggregation. Reference is made to a non-IMT band (as unlicensed band such as e.g. an ISM band) for use by an LTE-A system in carrier aggregation when a primary service (for the non-IMT band) does not appear, i.e. is not used or “active” in the non-IMT band. As shown in the upper part of the FIG. 1, the carrier in the IMT band is permanently assigned and/or available for use by e.g. the LTE-A system. In the lower part of FIG. 1, although a single carrier is shown only to keep the illustration and description easy, plural non-IMT bands may be present and exploited for carrier aggregation. A non-IMT band is typically assigned to a specific service (different from LTE-A or the like) which is referred to as a primary service for the non-IMT band. In periods in which the primary service is silent or inactive on the non-IMT band, the non-IMT band may be available for other services such as e.g. LTE-A, which may be referred to as secondary service (from the perspective of the non-IMT band).
Thus, as shown in FIG. 1, the non-IMT bands which are accessible with CR (Cognitive Radio) capability may include bands allowing secondary usage, e.g. C-band, TV White Space, or unlicensed equally usage e.g. ISM bands. Those bands can be categorized in two types:                predictable variance on usability and        unpredictable variance on usability.        
For instance, in TV white space, the incumbent TV broadcast service occupation is predictable (based on the “TV program”, for instance), while the incumbent wireless microphone service occupation is unpredictable. Then, the usability of this band is partially predictable, insofar as at least during the predicted TV broadcast duration, the band is not available for CR usage, while on other durations, the band usability is still unpredictable due to a potential use by a wireless microphone service. As another example, in the ISM band all the radio access technologies, RATs, have equal access right; hence, the ISM band is definitely unpredictable in terms of usability for LTE-A as a secondary service.
It is expected that an eNB (or BS) can provide for timely utilization of such non-IMT band when it is just available, or eNB can provide for timely release of such band when it is aware of an incumbent service. This shall maximize the efficiency of this band's utilization and more important, minimize potential interference to incumbent services.
For unpredictable bands, their utilization for the IMT system such as LTE-A is very opportunistically. Then, a fast understanding on situations prevailing in those bands is essential and corresponding signalling mechanism need to be designed to be quickly effective. It is assumed that predictable bands may be easier for eNB/BS configurations and because of their predictable character. But even in predictable condition, sometimes frequent variance on usability will still require more effective understanding on immediate imminent situations of those bands.
Thus, there is still a need to further improve such systems, e.g. communication systems operating in a carrier aggregation mode aggregating IMT bands as well as non-IMT bands.